Debuggers can currently start or stop the forward execution of a program at runtime. They can set points in the future execution of the code where a software developer wants the program execution to halt (breakpoints) based upon location in the source code or conditions of the program state (e.g., stop if a local variable contains a particular value). Execution can then be restarted from that point. Debuggers can also have a program execute and analyze execution for each line of source code or execute a portion of the source code without analyzing until a later point in the source code is reached. Frequently, software developers notice the symptoms of a problem with the program they are debugging long after the problem in the code has executed. At this point, the existing debuggers can only show the current state of the program or continue the execution of the program forward if the error permits.
These and other drawbacks exist with current systems.